An influential conservative group has warned its members about a potential Senate bid from Rep. Jeff Fortenberry, R-Neb.

The Senate Conservatives Fund declared, "BEWARE OF FORTENBERRY," in a Wednesday email.

"Congressman Fortenberry has a big-spending voting record in the House of Representatives and is not the kind of fiscal conservative we need in the U.S. Senate," the group's executive director, Matt Hoskins, wrote in the email. "In fact, he received a dismal 51% rating in the latest Heritage Action for America scorecard."

Fortenberry already publicly acknowledged his interest in running for retiring Sen. Mike Johanns' seat. But Nebraska Republicans are waiting for Gov. Dave Heineman to make a decision about the seat. They say the governor would clear the field if he ran for Johanns' seat.

In the meantime, ambitious Republicans are making preparations if Heineman does not run. The race could pit more establishment-backed Republicans against grass-roots-supported, more conservative candidates.

“It’s going to be the Wild West if the governor decides not to run,”said Jordan McGrain, executive director of the Nebraska Republican Party.

In addition to Heineman and Fortenberry, CQ Roll Call reported Wednesday that another Republican, former state Treasurer Shane Osborn, is interested in the race too.

Republicans also mentioned as possible candidates state Attorney General Jon Bruning and state Treasurer Don Stenberg, who both lost bids for Senate in 2012; the state’s three House members, Reps. Jeff Fortenberry, Adrian Smith and Lee Terry; and businessman Pete Ricketts.

But so far, only Fortenberry has attracted the ire of conservatives. In his email, Hoskins listed their problems with Fortenberry, which include his votes to increase the debt limit, raise income taxes and congressional pay, and ban incandescent light bulbs.

The Club for Growth, a group that often finds itself on the same side of primary battles as the SCF, remains mum on Nebraska. The club's spokesman said Tuesday the group will wait until candidates formally declare their campaigns before it weighs in on the race.

In 2012, both groups backed Stenberg. Sen. Deb Fischer, R-Neb., won the primary.